Maximum Inter-story Drift Ratio Research Articles

Optimum Semirigid Connections in Hybrid Frames for Effective Seismic Performance

The beneficial effect of using hybrid frames is realized in terms of the reduction of some desired engineering demand parameters (EDPs). However, this is achieved at the cost of increasing the values of some other EDPs as compared to the rigid frame. A good balance between the two can be achieved by selecting the optimum number of semirigid (SR) connections. In the present study, two schemes of the selection of the optimum number of SR connections are presented to obtain the desired benefit of the hybrid frame. One scheme provides the optimum number of SR connections which provides the desired reductions in the base shear (BS) and total number of plastic hinges formed (THmax) with the marginal increase in the maximum inter-story drift ratio (IDRmax). The other scheme provides the number of SR connections to be used for achieving the limiting drift allowed in the hybrid frame and accordingly, obtains the percentage reductions of the BS and THmax. Both schemes are developed using a graphical technique. Three illustrative examples are considered to demonstrate the efficacy of the two schemes using the nonlinear time history analysis under three types of earthquakes (i.e., near and far-field) at three peak ground accelaration (PGA) levels. The results of the study show that in both schemes of providing the optimum number of SR connections, significant reductions in the BS and THmax can be achieved as compared to the fully rigid frame. The corresponding IDRmax in the hybrid frames remains less than equal to the limiting value of the IDRmax prescribed in the literature.

Effects of aftershocks on the performance of steel building frames

Damages done by the earthquake excitation have attracted a significant amount of attention on aftershock effects on building structures. Seismic design of buildings is done without paying much attention to the repeated sequence of mainshock-aftershock events. It has been found that a structure may sustain the mainshock but is damaged during the aftershock. In this paper, the performance of steel building frames is evaluated with respect to the aftershocks followed by the mainshock. For this purpose, 4-, 8- and 12-story steel building frames are considered and are subject to synthesized earthquake, response spectrum compatible mainshock-aftershock sequences. For making the sequences, Bath’s law is applied. A nonlinear time history analysis is performed for a variety of synthesized sequences of the mainshock and aftershocks. The variation is implemented by selecting any single mainshock out of an ensemble of 8 mainshocks. In the sequence, a maximum of seven aftershocks followed by a mainshock is used. Time history record used for the analysis is developed by joining the synthesised earthquakes in series keeping a gap of of the 40 s between two events. The performance parameters used in the study are maximum inter-story drift ratio during an event (MIDR), residual inter-story drift ratio after the event (RIDR), maximum residual top story displacement and spread of hinges. The performances of the three building frames are compared in the study. It is seen that the 12-story frame is damaged to collapse level after 3 aftershocks, while the 4- and 8-story building frames survive seven aftershocks.

Seismic failure probability of adjacent frame structures retrofitted by flexible control measure

Due to the randomness of earthquake and the difference of dynamic characteristics of adjacent structures, the mechanical behavior of the adjacent structures under earthquake is very complex. A flexible control method using steel strands is proposed, which has little impact on the dynamic characteristics of the adjacent structures. A three-dimensional numerical calculation model of the adjacent frame structures is established by using LS-DYNA. The interstory drift ratios of the single structure, the adjacent uncontrolled structure and the adjacent controlled structure are analyzed by using incremental dynamic analysis (IDA) method. The failure probabilities of different limit states (LS) are studied based on the vulnerability, and the annual average and the design life failure probabilities are further discussed by the probabilistic seismic failure risk analysis. The results show that the maximum interstory drift ratio of the structure is reduced by the flexible control, and the failure probability of the adjacent controlled structure is less than that of the single structure and the adjacent uncontrolled structures. It should be noted that the influence of the flexible control on the failure probability is reduced when the PGA is close to 1.0 g. The four limit states LS1, LS2, LS3 and LS4 represent the slight damage, the moderate damage, the severe damage and the complete damage, respectively. The annual average failure probability from LS1 to LS4 decreases in turn, and the difference is about 10 times. Compared with the adjacent uncontrolled structures, the flexible control reduces the design life failure probabilities of the 10-storey structure and the 8-storey structure by 13.82% and 11.79%, respectively. The proposed control measure is helpful to reduce the failure probability of the adjacent frame structures under earthquake action.

Accurate Estimation of Inter-Story Drift Ratio in Multistory Framed Buildings Using a Novel Continuous Beam Model

This study presents a novel method for accurately predicting the dynamic behavior of multistory frame buildings under earthquake ground motion. The proposed method allows approximately estimating the inter-story drift ratio, a crucial parameter strongly associated with building damage, its distribution along the building height, and its maximum value location. An equivalent continuous beam model with a rotation at the base, consisting of a combination of a shear beam and a flexural beam, is proposed to achieve this. This model derives closed-form solutions for the building’s dynamic characteristics. The lateral deformations along the height of frame buildings subjected to a given earthquake load, particularly the inter-story drift ratio profiles, and the maximum inter-story drift ratio parameter, are investigated. The proposed continuous model requires two dimensionless parameters: the lateral stiffness ratio (α) and the rotation at the base (θ), representing the drift ratio of the first story. For the expression of the lateral stiffness ratio (α) coefficient, a simple equation is also proposed using the beam-to-column stiffness ratio (ρ, or Blume coefficient) associated with the framed (discrete) system. Various building models are employed to validate the proposed method, demonstrating its applicability to both high-rise and low-rise building configurations. With the results obtained, it is shown that the proposed continuous model can be used not only for high-rise or multistory building models but also for low-rise building models.

Probabilistic assessment of ground motion rotation impact on seismic performance of structures

In the common application of ground motions in seismic design and assessment, it is mainly inclined to leverage merely as-recorded components. However, the as-recorded data is restricted by the recording sensor orientations, implicitly neglecting other potential vectors, which can be readily calculated using a rotation matrix. Meanwhile, there exists a debate on the extent of the importance of such consideration on various aspects of seismic assessment outcomes. This study, using a measure of entropy, shows why and how rotating the ground motions matter, and to what extent the rotation can alter the structural seismic assessment results probabilistically, in the context of performance-based earthquake engineering. In this regard, two benchmark structures are analyzed and the sensitivity of their seismic behavior to the records' rotation is demonstrated using Sa(T1) and Maximum Inter-story Drift Ratio as the pair measures. It is revealed that the precise estimation of fragility functions is affected by the number of angles, unachievable using moderate ground motion sets at solely as-recorded angles. Fragility functions are developed through Cloud Analysis, and the impact of sample size and ground motion rotation on them is studied. Also, a simple yet versatile procedure is proposed to incorporate the mentioned impact in a cost-saving manner. In this regard, Sa,RotD50, which is a well-known seismological measure, is proven to contribute to the incorporation of waveform angular effects adequately. The proposed method is assessed in terms of its estimation precision in comparison with other single random angles probabilistically.

Collapse-based design method for simple seismic design of complex structural systems such as linked column frame system

Seismic design of structures is one of the most complex engineering sciences, in addition, the approaches that are currently used for analysis and design increase this complexity. Therefore, in this paper, a new method of seismic analysis and design of structures is presented, which not only eliminates the behavioral complexities of structures, but also increases accuracy. This method, which is called collapse-based design, is simple yet precise, using which even complex structural systems can be designed simply. For this purpose, linked column frame is considered for design as a new dual structural system that has complex, variable, and unclear seismic behavior. This structural system pursues specific target performance objectives and is designed with the aim of simple and quick repair after an earthquake. Currently, there is a lack of a suitable design method for the LCF system that leads to the design of optimal models with sufficient seismic capacity, hence this system is chosen as the prototype model. In the collapse-based design method, the structure is subjected to a seismic intensity equal to its collapse seismic intensity. The stability of the structure at this seismic intensity means sufficient seismic capacity and the maximum capacity of structural members can be used to maintain the stability. The first LCF model designed using this method is 8.5% lighter than a similar moment resisting frame model. The values of ductility and overstrength of this model are 7.56 and 3, and its maximum interstory drift ratio at the DBE and MCE hazard levels are 2% and 2.8%, respectively. Also, its collapse margin ratio is 2.28. But after the implementation of the target performance objectives, the weight of the model increases to 5% heavier than the similar moment resisting frame model, nevertheless, its seismic capacity decreases slightly. Based on this, it’s found that the implementation of the target performance objectives in the LCF system also causes little destructive effects. And as a final conclusion, the results show that the presented methods and approaches are appropriate for the analysis and design of structures and the comprehensive evaluation of designed models.

Classification of buildings' potential for seismic damage using a machine learning model with auto hyperparameter tuning

The research on the application of machine learning (ML) methods in the field of earthquake engineering shows a continuous and rapid progress in the last two decades. ML methods and models belonging to the category of supervised, unsupervised and semi-supervised learning are applied for the assessment of seismic vulnerability of structures and estimation of the expected level of seismic damage. These models lead to the classification of seismic damage into predefined classes through the extraction of patterns from data collected from various sources. However, the lack of detailed knowledge can affect their performance and ultimately reduce their reliability, as well as the generalizability that should characterize them. Towards this direction, the present paper attempts to compare and evaluate for the first time the ability of an extensive number of ML methods in the correct classification of R/C buildings at the first stage pre- and post-seismic inspection considering three seismic damage categories. A database consisting of 5850 training samples is used for this evaluation. This database is generated by solving 90 R/C buildings for 65 actual seismic excitations applying nonlinear time history analyses. For each one of the training samples the maximum interstory drift ratio is calculated as a damage index. In addition, a major contribution of this paper is the presentation and extensive documentation of the procedures required for the preprocessing of the data. Finally, an auto hyperparameter tuning method for the winning algorithm is proposed, so that the hyperparameters are automatically optimized utilizing Bayesian Optimization. The most significant conclusion extracted is that the studied ML algorithms extract very different classification results. In addition, the Support Vector Machine - Gaussian Kernel algorithm extracted the most accurate results of all the studied ML algorithms.

Inter-Story Drift Ratio Detection of High-Rise Buildings Based on Ambient Noise Recordings

The inter-story drift ratio (IDR) is a crucial parameter in structural health monitoring to judge the safety, stability, and serviceability of buildings. Real-time, continuous, and widely applicable detection on IDRs is essential. However, the current methods present some challenges in conducting such detection, including adverse effects from weather, the requirement for large amounts of space, and fragile instruments. This study proposes an alternative method to overcome these defects to measure IDRs and evaluate the structural conditions using ambient noise recordings. Ambient noise is a random and continuous wave signal with various sources and is modified by its propagating medium. Taking the Zhonghe Building on the campus of Tongji University, Shanghai, China, as an example, 24 three-component seismometers were deployed to capture and record the ambient noise continuously from 20 November 2021 to 9 December 2021. Using analysis of the polarization parameters of ambient noise during the building’s most dangerous time and ordinary time, a deflection curve, IDRs, and harmful IDRs of the Zhonghe Building during the most dangerous time were calculated. The computed maximum drift was 0.06 m, the maximum IDR was 1.140×10−3, and the maximum harmful IDR was −2.573×10−4. These results were compared with the relevant specifications in China, and it was found that the structure was in good condition. The study proposes an alternative method to measure IDRs with high applicability and continuity in real time and underscores the need for further research to achieve a localized and real-time structural health monitoring system.

Machine Learning-Based Rapid Post-Earthquake Damage Detection of RC Resisting-Moment Frame Buildings

This study proposes a methodology to predict the damage condition of Reinforced Concrete (RC) resisting-moment frame buildings using Machine Learning (ML) methods. Structural members of six hundred RC buildings with varying stories and spans in X and Y directions were designed using the virtual work method. Sixty thousand time-history analyses using ten spectrum-matched earthquake records and ten scaling factors were carried out to cover the structures’ elastic and inelastic behavior. The buildings and earthquake records were split randomly into training data and testing data to predict the damage condition of new ones. In order to reduce bias, the random selection of buildings and earthquake records was carried out several times, and the mean and standard deviation of the accuracy were obtained. Moreover, 27 Intensity Measures (IM) based on acceleration, velocity, or displacement from the ground and roof sensor responses were used to capture the building’s behavior features. The ML methods used IMs, the number of stories, and the number of spans in X and Y directions as input data and the maximum inter-story drift ratio as output data. Finally, seven Machine Learning (ML) methods were trained to predict the damage condition of buildings, finding the best set of training buildings, IMs, and ML methods for the highest prediction accuracy.

Shaking‐table test results of a full‐scale free‐standing building with base sliding and rocking

AbstractThis paper present results of shaking‐table tests conducted in 2015 and 2018 on a free‐standing base sliding and rocking system, which allows sliding and uplifting. A full‐scale 10‐story reinforced concrete (RC) building equipped with cast iron plates on the bottom surface of the grade beams was used as a specimen for 2015 and 2018 experiments. In 2018, the static friction coefficients of the specimen were 0.48 and 0.49, which was higher than that of the rustproofed specimens in 2015. In the experiments of 2015 and 2018, the normalized base shear (NBS) values when the sliding length of the building reached ≥1 mm were 0.0035–0.1795 and 0.1744–0.2748, respectively. In the shaking‐table test corresponding to moderate earthquake motions, the 2018 specimen showed almost no lateral movement, whereas the 2015 specimen moved laterally. Therefore, more seismic energy was input into the specimen, and the maximum interstory drift ratio of the 2018 specimen was larger than that of the 2015 specimen. However, when the 50% amplitude excitation results of the 2015 seismic structural system are compared with those of the 2018 free‐standing structural system, the 2018 results are approximately 0.57 times smaller. Thus, a free‐standing structural system with cast iron plates to reduce earthquake energy could reduce damage to buildings. The 2018 specimen satisfies the concept of a free‐standing base sliding and rocking system that does not move laterally during small to moderate earthquake motions but moves laterally during strong earthquake motions to suppress structural damage.

Energy-based procedures for seismic fragility analysis of mainshock-damaged buildings

In recent decades, significant research efforts have been devoted to developing fragility and vulnerability models for mainshock-damaged buildings, i.e., depending on the attained damage state after a mainshock ground motion (state-dependent fragility/vulnerability relationships). Displacement-based peak quantities, such as the maximum interstory drift ratio, are widely adopted in fragility analysis to define both engineering demands and structural capacities at the global and/or local levels. However, when considering ground-motion sequences, the use of peak quantities may lead to statistical inconsistencies (e.g., fragility curves’ crossings) due to inadequate consideration of damage accumulation. In this context, energy-based engineering demand parameters (EDPs), explicitly accounting for cumulative damage, can help address this issue. This paper provides an overview of recent findings on the development of aftershock-fragility models of mainshock-damaged buildings. Particular focus is given to state-of-the-art frameworks for fragility analyses based on cumulative damage parameters. Moreover, a literature review on damage indices and energy-based concepts and approaches in earthquake engineering is reported to better understand the main advantages of the mostly adopted energy-based parameters, as well as their limitations. Different refinement levels of seismic response analyses to derive fragility relationships of mainshock-damaged buildings are also discussed. Finally, the benefits of adopting energy-based EDPs rather than, or in addition to, peak quantities in state-dependent fragility analyses are demonstrated on a reinforced concrete frame building. Specifically, a refined lumped plasticity modeling approach is adopted, and sequential cloud-based time-history analyses of a Multi-Degree-of-Freedom (MDoF) model are carried out. The results highlight that energy-based approaches for fragility analysis effectively capture damage accumulation during earthquake sequences without inconsistencies in the obtained statistical models. On the other hand, estimating global or local structural capacity in terms of cumulative EDPs is still challenging. Further experimental data are needed to better calibrate the quantification of energy-based damaged states.

Fragility framework for corroded steel moment-resisting frame buildings subjected to mainshock-aftershock sequences

This study proposes a framework for the seismic fragility assessment of steel moment-resisting frames exposed to different rates of corrosion and subjected to real mainshock-aftershock (MS-AS) sequences. The inherent uncertainties in the structural characteristics may significantly affect the structural performance. Thus, in addition to the demand parameters, the framework considers randomness in the capacity parameters using the Latin hypercube sampling. Three frames are modeled in OpenSees and then subjected to nine real as-recorded MS-AS sequences to illustrate the application of the framework. Four limit states are defined based on the maximum interstory drift ratio and the multiple stripe analysis is chosen for the fragility assessment. The presented framework allows for the plot of the fragility surfaces for each corrosion level conditioned on both the mainshock and the aftershock intensity. The results indicate that corrosion and aftershock may significantly affect the seismic fragility especially for the extreme limit states.

Seismic performance of RC frames with self-centering precast post-tensioned connections considering the effect of infill walls

This paper presents the seismic performance evaluation of self-centering precast post-tensioned concrete (SCPPTC) frames with infill walls. The SCPPTC connection system consists of all-steel bamboo-shaped energy dissipaters (SBED) and prestressed tendons, which provide energy dissipation capacity and self-centering capability, respectively. Using modeling parameters calibrated with experimental tests, nonlinear numerical models of SBED, SCPPTC connection, infill walls, and 2D SCPPTC frames were developed in OpenSees, to compare the performance of the structures with different types of infill wall layouts. Nonlinear static pushover and incremental dynamic analysis (IDA) were performed to study the effect of infill walls on the overall response of SCPPTC frames, in terms of stiffness, strength, maximum interstory drift ratio,θmax, the maximum residual interstory drift ratio, θr,max, and the normalized post-tensioned force. Using the IDA results, the study also developed fragility curves and estimated the collapse margin ratios. The results demonstrated that the shear strength of the SCPPTC frame was improved from 4.19% to 12.2%, and the initial secant stiffness of the SCPPTC frame was augmented from 22.9% to 88.3% with increasing filling rate. The totally infilled SCPPTC frame (SCPPTC-ToI) exhibits a 19.86% lower θmax than that of pilotis-infilled SCPPTC frame (SCPPTC-PiI) under rare earthquakes, and the maximum prestress of SCPPTC-ToI was also 7.14% lower than that of SCPPTC-PiI. With the increase in filling rate, θr,max increased by a maximum of 120.45%. The pronounced soft layer led to the highest failure and collapse probabilities of SCPPTC-PiI among all SCPPTC frames at the same performance level.

Seismic Damage “Semaphore” Based on the Fundamental Period Variation: A Probabilistic Seismic Demand Assessment of Steel Moment-Resisting Frames

During strong earthquakes, structural damage usually occurs, resulting in a degradation of the overall stiffness of the affected structures. This degradation produces a modification in the dynamic properties of the structures, for instance, in the fundamental period of vibration (T1). Hence, the variation of T1 could be used as an indicator of seismic structural damage. In this article, a seismic damage assessment in four generic typologies of steel buildings was carried focused on verifying the variation of T1. To do so, several seismic damage states were calculated using the maximum inter-story drift ratio, MIDR, and following the Risk-UE guidelines. Then, a series of probabilistic nonlinear static analyses was implemented using Monte Carlo simulations. The probabilistic approach allows one to vary the main mechanical properties of the buildings, thus analyzing in this research 4000 buildings (1000 building samples for each of the four generic typologies). The variation of T1 was estimated using the capacity spectrum, and it was related to the MIDR for each damage state. As a main result of this study, the expected variation of T1 for several damage states is provided. Finally, a proposal for a seismic damage preventive “semaphore” and fragility curves are presented. These results may be useful as parameters or criteria in the evaluation of on-site structural monitoring for steel buildings.

A design method for seismic retrofit of reinforced concrete frame buildings using aluminum shear panels

Despite significant progress in research and development of aluminum shear panels in recent decades, their implementation for seismic retrofit of existing reinforced concrete (RC) buildings can still be significantly extended. Their application is limited by the general lack of relatively simple and effective design criteria and proper guidelines. This paper develops a design method for the seismic retrofit of reinforced concrete buildings using aluminum multi-stiffened shear panels as dampers. Both the nonlinearity in the structure and the dampers-structure interaction are considered to give an optimal distribution of the shear panels over the height of the building. The analytical laws refer to dissipative aluminum shear panels recently tested and analyzed by the authors. The proposed procedure has been described in detail. Its applicability has been demonstrated by analyzing two typical RC buildings having drift capacity-to-demand ratios ranging from 0.505 to 0.624. The design value of the panel-to-frame stiffness ratio has been found to range from 0.594 to 1.432 as a function of the lateral stiffness of the existing building. The verification of the proposed procedure has been carried out by checking the validity of the design assumptions. The first one (i.e., the mode shapes remain the same before and after retrofit) has been checked using the modal assurance criterion that gives values ranging from 0.992 to 0.998. The second one (i.e., uniform yield drift distribution over the building height) has been checked by comparing the yield drifts with their average value giving a standard deviation ranging from about 11 to 15%. The effectiveness of the design method has been finally validated through nonlinear time-history analysis for different seismic accelerograms and hysteresis models. The results show that the seismic retrofit design procedure is effective in significantly reducing inter-story drift (maximum inter-story drift ratio demands ranging from 1.04 to 2.07%) thus satisfying the acceptance criteria of the building, and avoiding drift concentration and consequential weak story collapse.

Machine learning-based seismic response and performance assessment of reinforced concrete buildings

Complexity and unpredictability nature of earthquakes makes them unique external loads that there is no unique formula used for the prediction of seismic responses. Hence, this research aims to implement the most well-known Machine Learning (ML) methods in Python software to propose a prediction model for seismic response and performance assessment of Reinforced Concrete Moment-Resisting Frames (RC MRFs). To prepare 92,400 data points of training dataset for developing data-driven techniques, Incremental Dynamic Analyses (IDAs) were performed considering 165 RC MRFs with two-, to twelve-Story elevations having the bay lengths of 5.0 m, 6.1 m, and 7.6 m assuming near-fault seismic excitations. Then, important structural features were considered in datasets to train and test the ML-based prediction models, which were improved with innovative techniques. The results show that improved algorithms have higher R2 values for estimating the Maximum Interstory Drift Ratio (IDRmax), and two improved algorithms of artificial neural networks and extreme gradient boosting can estimate the Median of IDA curves (M-IDAs) of RC MRFs, which can be used to estimate the seismic limit-state capacity and performance assessment of existing or newly constructed RC buildings. To validate the generality and accuracy of the proposed ML-based prediction model, a five-Story RC building with different input features was used, and the results are promising. Therefore, graphical user interface is introduced as user-friendly tool to help researchers in estimating the seismic limit-state capacity of RC buildings, while reducing the computational cost and analytical efforts.

Two-Parameter–Based Damage Measure for Probabilistic Seismic Analysis of Concrete Structures

Traditional seismic fragility analysis defines the structural damage measure (DM) as a single parameter based on either strength, displacement, damage, or energy to evaluate the postearthquake performance of the structure, thus it is difficult to fully catch the behavior characteristics of the structures, e.g., both the maximum deformation capacity and the repairability of the structure. In this paper, we developed a multiparameter-based DM (mDM) index (here actually two parameters) for the probabilistic seismic analysis of reinforced concrete (RC) structures to capture a more comprehensive view of structural performance. Two parameters (i.e., the maximum interstory drift ratio θmax and the maximum residual interstory drift ratio θr,max) are combined to represent the overall structural performance, and different combination rules are investigated. To verify the superiority of the proposed mDM, the fragility analysis of three different structures is conducted, i.e., ordinary RC structure, aging RC structure, and new self-centering structure. The fragility curves derived from single DM and mDM are compared, and it is found that fragility curves with mDM can reflect both the maximum displacement and residual displacement features of the structure, thus mDM gives a more comprehensive and synthesis assessment of the postearthquake performance of the structure, which is beneficial for informed decision-making.

Site dependent response estimation by holistic record selection and bagging algorithm

An efficient two-step method is proposed for site-specific structural response estimation of buildings at multiple sites with different seismicity. In the first step, holistic record sets that cover a range of seismic characteristics are constructed for a few intensity measure levels. Next, using the holistic sets and their associated responses, any required response measure (e.g., structural collapse) is calculated using a bagging algorithm. The proposed method has two advantages to many similar suggested processes in this regard. Because the proposed process works directly with record selection methods and a computational method, it can consider the effect of different ground motion intensity measures and works for all engineering demand parameters. The performance of the proposed method is investigated using two 4 and 8-story steel moment-resisting frames in six cities with different seismicity. The collapse fragility curve, maximum inter-story drift ratio (MIDR), and peak floor acceleration (PFA) are considered for performance assessment. It was observed that when the number of selected records is about twice the common required number of records for response assessment, the proposed method, on average, leads to equal or better efficiency for collapse fragility estimation compared to conventional single site-building analysis. Also, the results indicate an efficiency similar to utilizing about 10–20 ground motion records at each IM level for MIDR and PFA response estimation.

Hybrid Test of Precast Concrete Frame with Energy-Dissipation Cladding Panel System

To investigate the influence of an energy-dissipation cladding panel system (EDCPS) on the dynamic responses of a precast concrete (PC) frame structure, a six-story, three-span planar frame structure with an EDCPS (called “damping structure”) and a counterpart planar bare frame structure (called “bare frame structure”) were designed. The middle span and bottom two stories of the frame were selected as the test substructures, whereas the rest were considered using the numerical substructure. Hybrid tests were conducted on the two structures under four earthquake levels. The test results indicated that the damage evolution characteristics of the PC frame were not affected by the introduction of EDCPS. The dampers in the EDCPS successfully yielded and dissipated seismic energy under the four earthquake levels. Moreover, the maximum inter-story drift ratio of the damping structure was reduced by 12.59%, 17.68%, and 10.34% under the design-basis earthquake, maximum considered earthquake, and very rare earthquake, respectively, exhibiting a satisfactory damage-control effect. The cladding panels remained intact under the four earthquake levels, indicating that this structure effectively prevents damage to the cladding panels. Finally, a numerical simulation method is recommended according to the damage characteristics of the damping structure and is validated against the test data.

Vibration control of seismic forces using viscous dampers and buckling restrained braces in irregular composite buildings

This study addresses the effectiveness of buckling restrained braces (BRBs) and viscous dampers (VDs) in dissipating seismic energy and increasing the seismic performance of irregular composite buildings during earthquake events. The seismic response of steel-concrete composite moment resisting frames of 15 stories with concrete filled steel tubes (CFST) as columns and composite beams was examined with and without seismic protection devices by employing ETABS software using the response spectrum method as per IS 1893:2016 for seismic zone V. Regular and irregular plans characterised the structures. The plan irregular buildings include C and L-shaped buildings. The BRBs and VDs were installed on all the buildings in two configurations: corner bays and centre bays throughout the height. The results showed BRBs and VDs excellent energy dissipation capabilities. VDs contributions were 5%-8% more than BRBs and, therefore, more efficient. Centre bays placement of VDs was most efficient for regular buildings reducing time-period by 60%, maximum story displacement by 57%, base shear by 37%, and maximum interstory drift ratio by 70%. Corner bays placement of VDs was most efficient for C and L-shaped buildings reducing time-period by 55%-60%, maximum story displacement by 63%-65%, base shear by 30% and 13%, and maximum interstory drift ratio by 78%-80%, respectively, making viscous dampers an excellent choice for midrise composite buildings.